MrSandman

I've posted about this before.. but was wondering if any of you had more insight into what might be causing this.

Background:

Car is v6 automatic

Sound only occurs during acceleration.

Sound only occurs from 78-81 mph while accelerating. If I let off the gas at those speeds, the sound goes away. The sound always occurs under this scenario.. does not matter how warmed up the car is.. or the temp outside.

Sound first occurred when I had nothing more than single axleback and CAI+Tune. I have since replaced the exhaust from the cats back (xpipe with GTAs), and upgraded rear with 3.73 gears.

Adding the gears did not change the mph range at which this noise occurs (not rpm related).

Sound is present regardless of what tune I use (brenspeed 87-93, or bama 93 race).


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It sounds like a metal to metal (high frequency rattle) coming from around the transmission or back part of the engine bay.

I have removed the "fake" exhaust hangers attached to the transmission crossmemeber and bent the exhaust hangers away from the crossmember per the instructions in the rattle TSB.

The only thing I can think of is that it might be the spacer plate issue.. even though the v6 was never mentioned in the TSB (at least I don't think so.. I have never actually seen the TSB for this). I think the v6 and GT auto transmissions are basically the same.. so this should apply; however, the people that have had this fixed don't report the problem they had as a rattle occurring at those speeds.

Anyone have any other ideas? I'm too chicken to take my car to the dealer right now.. and the worst thing to have a dealer investigate is a strange noise that only occurs when you are speeding

crazyassracer

You say it's from the front of the car?
I've got the same sound under the same situation, but I thought it was coming from the back half of the car.
Couldnt track it down so I just turned the stereo up.

Texotic

i have no idea... good luck trying to figure out what it is, though.

MrSandman

I've only been in the driver's seat when it happens.... but pretty sure it's coming from under the center console area (transmission) or the back part of the engine by the firewall. I can't hear it with the radio on... but is sounds horrible... not too loud.. but not the kind of sound you want coming from your car. Maybe I can get my wife to drive at that speed while I put my ear to the center console

crazyassracer

Ha!
I've had my wife laying halfway in the trunk while I drove around town to confirm that my new exhaust was tapping the suspension.
Probably not the best date she was ever on.

grampa_stang

I have an auto and had a rattle. My rattle turned out to be the O/D button itself. Resolved that by shoving a small strip of felt w/sticky backing around the button. Yours is probably different though..but, ya never know.

MrSandman

Nope, but thanks for the suggestion. This sound is more like a metal to metal high frequency, almost grinding sound that is definitely not coming from the inside of the car. I don't think it's causing any harm.. but it's really hard to ignore. When driving long distances, it's hard for me to stay out of the 80 mph range.

Based on the properties I've mentioned (noise only occurs during "load" at certain speed), anyone have guesses?

MrSandman

Holy crap.. I was so wrong about this.
First off... after paying closer attention.. I noticed that you actually could hear it at other speeds... it was the rpm (2500) which was consistent... the tinny vibration noise was just much more prominent when it was consistently at that rpm (duh).

After realizing that, I took another look under the car and in the engine bay.. and tightened a few things up.. still didn't work.

Yesterday, I had an epiphany and decided that it has to be the heat shield in the passenger side header.. Even though everything was tight.. and clearances looked/felt normal..(i've checked the thing a million times).

I popped the hood.. grabbed a broom stick.. and pushed it in-between the header and the shield (inner and outer portion).. which added about an inch of extra space.

Drove to work this morning... and no more noise at 80mph. Thank God...!!! This was driving me CRAZY!!!!!.

sailing220

I was just about to say "heat shields" before I read your last post. Good catch.

crazyassracer

Sure, having the rattle gone is a plus, but that smoldering broom stick poking out of the engine bay, looks a bit odd going down the road.